ABSTRACT Pediatric asthma is the most common chronic disease among children in the United States (US) and the leading cause of emergency department visits, inpatient pediatric hospitalization and missed school days. A key component of asthma prevention involves minimizing exposure to risk factors for asthma onset and effective asthma management requires the avoidance of triggers for asthma exacerbation. If asthma is well-managed, the vast majority of children with asthma can live symptom-free. Decades of research has identified secondhand tobacco smoke (STS) as a risk factor for asthma onset and exacerbation. The dissemination of this information via public health education programs has resulted in reductions in prenatal tobacco use and decreased exposure to STS among youth. Still, recent data suggest that STS exposure remains significantly higher among children ages 3-11, relative to teenagers and adults, potentially due to exposure in the home. Legalization of cannabis is growing rapidly across the US. Not surprisingly, cannabis use has increased more rapidly among adults in states where it has been legalized. Further, in contrast to declines in cigarette use, our recent work shows that cannabis use is increasing rapidly among parents with children in the home. While this is occurring among both parents who are cigarette smokers and among non-smokers, cannabis use is more than twice as common among cigarette smokers. Over 50% of children with asthma in the US live with a smoker. With the rapid legalization of marijuana across the country, systematic investigation of the potential impact of adoption of medical marijuana laws (MML) and recreational marijuana laws (RML) children?s respiratory health is urgently needed at a population level. To this end, the current study uses an ecological design to estimate key pediatric asthma outcomes before and after the adoption of MML and RML using nationally representative data collected between 1996 and 2022. Ecologic studies can be a critical first step in identifying key public health problems. An evidence base on the potential impact of the adoption of MML and RML on children?s respiratory health is essential to inform current and evolving policy, clinical and community interventions, and prevention programming needs in order to avert potentially unintended risks associated with cannabis popularization: increased exposure to secondhand cannabis smoke among children.